A hybrid circuit breaker consisting of a high speed mechanical switch and a power semiconductor device has advantages such as large discharge capacity, fast turn-off speed, and strong current-limiting capability and so on and thus has become a hot issue to study in the field of breaking a large-capacity system. Compared with other hybrid solutions, a hybrid DC circuit breaker that breaks current using a power semiconductor device with a full control function has a faster separating speed and facilitates separation of rational current. However, when separating current using the full-control type power semiconductor device, its current transfer loop usually needs a full control type power semiconductor device to cut the current, resulting in a high control complexity and cost, which restricts its promotion and application.
In a traditional transfer current circuit, a capacitor charging circuit is directly connected to a main loop without isolation; during a breaking process, a charging power source and the main loop will suffer interference; besides, it is highly demanding on voltage withstanding of the main loop charging power source, and the breaking is unreliable.
Traditional DC circuit breakers cannot handle the requirements of two-way limitation and separation fault current when tide current in a DC grid is uncertain; or in order to satisfy two-way work scenarios, the size and manufacturing cost of the circuit breakers will always increase significantly.
Because system impedance of a DC power system is very small, when a short-circuit fault occurs, the fault current rises very quickly with a large current amplitude; therefore, it is highly demanding on the current breaking capability of DC circuit breakers, such that the manufacturing technology of the DC circuit breakers is rather difficult with a high manufacturing cost.